Purdue freshman QB Danny Etling made some plays on the Michigan State defense. The Spartans next four opponents have much more experienced and dangerous quarterbacks that could exploit State's defense.Mike Mulholland | MLive.com

EAST LANSING — Much has been learned about the Michigan State football team seven games into the season.

It's alarming, however, that there's still much we can't be too certain of with these Spartans.

Everyone knows, it's what you don't know that can hurt you most.

Here are five things we DON'T know about Michigan State entering the Illinois road game this Saturday.

1. Can Michigan State handle success?

Small college towns make for big egos in collegiate athletics, and the Spartans' players have begun talking a lot about Roses and Red Zone and defensive rankings of late.

Defensive coordinator Pat Narduzzi said the defense didn't have a good week of practice for Purdue, and Michigan State struggled to beat the woeful Boilermakers, 14-0, after the Purdue had been outscored 140-41 in their previous two contests.

The Spartans seem pretty confident for a team that has played the 104th-ranked schedule, can't crack the Top 25 rankings and have yet to prove they can gut out a close win, folding on offense, defense, special teams and the coaching box in the only marquee matchup of the season in South Bend, Ind.

2. Is Connor Cook the QB of the future?

Back-to-back, strong performances against Iowa and Indiana seemed to indicate Cook was the best choice to lead the Spartans into the stretch run this season.

But an inexplicable, shaky performance against Purdue — one of the worst defenses in the nation — has to make you wonder.

I suggested to Dantonio it might have been the wet ball in the first half, but Dantonio wanted no part of that excuse.

"I don't think that had a lot to do with it,'' Dantonio said. "I think we missed some reads and missed some throws, quite honestly.''

Cook is on the clock; he might survive as QB the rest of this season by default, but if Michigan State falls short of its goals this season ...

3. Is Jeremy Langford fool's gold at tailback?

Langford ripped off some chunks of yardage against Purdue, but doesn't everybody?

Langford's longest run in 128 career carries is 32 yards.

Freshman Delton Williams has a 37-yarder in 24 carries — and Williams hasn't had the benefit of many carries against the sorry defenses Langford has faced this season.

Having speed is one thing. But having the vision to find running lanes and the hunger and stamina to break tackles is another.

4. Is the defense a paper tiger?

Purdue ran the ball down Michigan State's throat on its opening drive last Saturday. The defense adjusted, but not before we saw the Spartans get knocked off the ball by arguably the worst rushing attack in the Big Ten.

What will happen against a quality run attack? Nebraska, anyone?

Then, the secondary.

We all saw what happened against Notre Dame — the only decent, balanced offense the Spartans have played this season.

A couple of the pass interference calls on the cornerbacks were questionable against the Irish, yes. But a couple of them weren't.

Indiana had receivers running past safeties Kurtis Drummond and Isaiah Lewis the whole game, and with better protection State would have been exploited for more than just Shane Wynn's 53-yard reception.

Western Michigan had a 45-yard pass, Iowa a 47-yarder and even Purdue struck gold for 43 yards.

Illinois has a good passing game, and the schedule is starting to get tougher. Stay tuned.

5. Are the marquee receivers too soft for prime time?

Receivers coach Terrence Samuel is off the hook, he has coached them up and the drops have vanished.

So now Bennie Fowler is out with a hamstring, and Aaron Burbridge got knocked out by Purdue.

Macgarrett Kings and Tony Lippett are carrying the load, admirably.

But Fowler and Burbridge were supposed to be the stars and have both shown when they are focused and motivated they can make big-time plays.